1. Field of the Invention
The invention relates to a weighing system with a plurality of weighing cells for separately weighing a plurality of materials.
2. Description of the Related Art
Weighing cells are functional units for determining weight, which include a weighing unit within a housing and the electronics necessary for operation. The weighing cells also store the calibration parameters specific to the weighing unit. The downstream electronics, e.g., the signal processing unit, may be arranged either within or outside the weighing cell.
A person skilled in the art will be familiar with multiple arrangements of individual weighing cells in weighing systems. Such cells are required in industrial processes wherever the weight of many individual small amounts of material, whose individual weight is often very low, must be determined at short time intervals. Examples include, among others, dosing and quality monitoring processes, e.g., in the pharmaceutical industry.
When deciding the size of a weighing cell, the geometric size of the weighing unit is considered. Since the geometric size of the weighing units suitable for such processes are large in relation to the material being weighed, the weighing cells are almost exclusively provided in single-row, linear arrangements. Only when particularly narrow weighing units are used is it possible to space the individual load sensors closely together.
Geometrically larger weighing units may also be staggered in height, such that special arms fixed to the force application points of the weighing units make it possible to space the individual load sensors closely together. The separate arms on the weighing units differ individually depending on the position of the weighing cell within the weighing system. Such an arrangement is known in U.S. Pat. No. 6,615,638 B1. The cost of designing and building weighing systems of this kind is very high because each separate weighing cell within the weighing system differs individually. This also presents problems when such weighing systems have to be serviced and repaired. Functionally reliable arrangements of weighing cells, e.g., in a two-dimensional array, with closely spaced individual load sensors at distances ranging from one to five centimeters, and a positional tolerance of the load sensors of a few tenths of a millimeter, can be realized with conventional weighing cells only at great cost.